Mexico's security commission says federal troops will replace local police in 32 municipalities, in a bid to contain drug gangs that have fuelled a surge in violence and often operate in league with local police.

Secret orders warning of an increased risk of insider attacks were never passed on to three Australian diggers killed by an Afghan soldier in August 2012.

The documents gave orders for security to be stepped up at remote bases where coalition soldiers were working with their Afghan counterparts.

The three diggers who died – Private Robbie Poate, Lance Corporal 'Rick' Milosevic, and Sapper James Martin – were gunned down at a patrol base in a Taliban stronghold.

"The intelligence that was known further up the chain of command just didn't make it down there ...had it got down, they would've taken their security far more seriously than they did," Robbie Poate's father Hugh said.